1. Field of the Invention
The present invention relates to a vehicular air bag, an air bag module having the air bag and a method of folding the air bag.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2004-58848 (=JP2004058848) discloses an air bag 11 received at a vehicular interior upper part, where the air bag 1 protects a vehicular occupant head part at a sideward collision. The air bag 11 has such a structure that a base end thereof on an upper side is fixed to a side roof rail RR at a vehicular body upper part. With the above structure, the air bag 11 is installed in a space between the side roof rail RR and a head lining, in a such condition that an entirety of the air bag 11 is folded, from a leading end side, in a form of roll. A gas of an inflator 33 expands the air bag 11 at the sideward collision, a lower end part of the head lining is pushed and opened toward a vehicular interior side, thereby developing the air bag 11 downward, thus protecting the vehicular occupant head part.
According to the above conventional technology where the air bag 11 has a roll part wound in the form of roll from the leading end side, however, the thus folded air bag 11 is caused to have an enlarged cross section. In other words, winding tightly the roll part of the air bag 11 makes the winding operation difficult and increases resistance caused by rewinding when the air bag 11 is expanded. Therefore, it is necessary to loosely wind the roll part, thereby enlarging the entirety of the air bag 11 (having the roll part) in cross section.
Consequently, for installing, in the space between the side roof rail RR and the head lining, the air bag 11 having the large cross section in folded state, it is necessary to secure a large space. Due to the large space, the head lining is positioned toward the vehicular interior side, resulting in oppression of the vehicular interior space.